We have ALOT of bananas growing in our backyard. I freeze them all the the time. Peeled and cut into smaller pieces though. i have never defrosted them to mash for a baby though.. sue they'd be fine. I generally put them in cakes, smoothies or make the worlds easiest banana ice-cream. If you wizz frozen banana pieces in a food processor, after about 3 minutes, it changes consistency and becomes creamy, It is just like banana ice-cream. i wouldn't believe it if i hadn't seen it myself. It is such a great treat for the kids as it is just banana. YUM!